Diphenhydramine hydrochloride: adverse event reports filed with FDA

5,556

reports as suspect product

0% of all reports · about 277 a year

538

reports, 12 months to June 2026

671 in the 12 months before

94.6%

marked serious by the reporter

57.7% across the class

47.8%

record death among outcomes, as reported

2,655 reports · not verified by FDA

Reports by month, five years

Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.

By year received

2026 covers reports received through June 2026 only.

Reactions recorded in the reports

share of Diphenhydramine hydrochloride reports recording the termmedian drug in histamine-1 receptor antagonist

1. Toxicity to various agentspoisoning or toxic effect of one or more substances23.5%1,307
2. Drug ineffectivethe medicine did not work as expected21.1%1,175
3. Fatiguetiredness17.7%985
4. Painpain, site not specified17.5%970
5. Headachehead pain16.3%908
6. Rheumatoid arthritisrheumatoid arthritis, an inflammatory joint disease15%836
7. Nauseafeeling sick14.7%818
8. Off label useused for a purpose or in a way not on the label14.4%802
9. Infusion related reactiona reaction during or soon after an infusion14%779
10. Pyrexiafever12%667
11. Arthralgiajoint pain11.1%617
12. Hypersensitivityan allergic-type reaction10.9%603
13. Hypertensionhigh blood pressure10.5%583
14. Malaisegeneral feeling of being unwell10.2%567
15. Rashskin rash9.9%552
16. Drug hypersensitivityan allergic-type reaction to a medicine9.9%549
17. Drug abusemisuse of a medicine9.4%521
18. Vomitingbeing sick9.2%509
19. Hepatic enzyme increasedraised liver enzymes9.1%505
20. Joint swellinga swollen joint8.6%479
21. Dizzinesslight-headedness or unsteadiness8.3%460
22. Diarrhoealoose or frequent stools8.1%450
23. Weight decreasedweight loss8%442
24. Nasopharyngitisa cold7.9%437
25. Macular degenerationa disease of the central retina7.7%427
26. Sinusitissinus infection7.6%425
27. Overdosea dose above the recommended amount7.5%419
28. Hypoaesthesianumbness7.4%411
29. Anxietyanxiety7.3%405
30. Condition aggravatedthe condition being treated got worse7.3%405

Top 30 of 982 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 34 drugs in the histamine-1 receptor antagonist class; it describes the reports, not the patients. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Outcomes recorded

Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 135,666 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."

Patients and reporters

Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 52.9% of reports give the United States as the country of the event or reporter.

Reason for use recorded

The indication field is filled in by the reporter and is often blank; shares are of all 5,556 reports.

Drugs most often listed in the same reports

Other products listed in reports where Diphenhydramine hydrochloride is a suspect product, whatever their own role. Co-listing means the two were recorded together; it says nothing about either product's part in the event. Only the 2,500 most-reported names are counted here.

In context

Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Other drugs in the histamine-1 receptor antagonist class

Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." A brand and its generic are separate rows because reporters name them separately.

Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A report counts here when it lists Diphenhydramine hydrochloride as a suspect or interacting product; reports listing it only as a concomitant medication (16,027) are excluded. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.